Lakeweed control underway in Waitaki Lakes

Work to manage the invasive lakeweed lagarosiphon in South Canterbury’s Waitaki hydro lakes will begin next week.

Toitū Te Whenua Land Information New Zealand (LINZ) is leading a targeted control programme to reduce the impact of lagarosiphon on recreational activities like swimming, fishing and boating, as well as hydroelectric operations. The programme also focuses on preventing lagarosiphon from spreading from the lake to other waterways.

LINZ Leader Biosecurity Tracey Burton says divers will remove the weed from around boat ramps and valued recreational areas throughout the Waitaki Lakes. Herbicide control will also take place on dense weed beds throughout the Ahuriri Arm in Lake Benmore. In addition, surveys will be undertaken in the lagarosiphon-free Lakes Ruataniwha and Ōhau, and the Haldon Arm of Lake Benmore.

“This work is essential to safeguard these lakes and prevent lagarosiphon from becoming further established in the system,” Burton says.

Lagarosiphon can spread easily - even a fragment the size of a fingernail can lead to infestation. It forms tall, dense beds that can overtake lakes, choke waterways, smother native plants, and interfere with hydroelectric power generation and recreational use.

Because lagarosiphon is easily spread through human activity, lake users play a crucial role in preventing its movement between waterbodies.

“Please remember to Check, Clean and Dry your water gear between waterways,” Burton says.

“This simple step helps prevent invasive species from being spread to other lakes.”

The control work is funded by LINZ, Meridian Energy, and Environment Canterbury.